1. The Field of the Invention
The present invention generally relates to the field of light curing devices and, more specifically, to light curing devices incorporating light emitting diodes (LEDs).
2. The Relevant Technology
In the field of dentistry, dental cavities are often filled and/or sealed with photosensitive compounds that are cured by exposure to radiant energy, such as visible light. These compounds, commonly referred to as light-curable compounds, are placed within dental cavity preparations or onto dental surfaces where they are subsequently irradiated by light. The radiated light causes photosensitive components within the compounds to polymerize, thereby hardening the light-curable compounds within the dental cavity preparation or another desired location.
Existing light-curing devices are typically configured with a light source, such as a quartz-tungsten-halogen (QTH) bulb or an LED light source. QTH bulbs are particularly useful because they are configured to generate a broad spectrum of light that can be used to cure a broad range of products. In particular, a QTH bulb is typically configured to emit a continuous spectrum of light in a preferred range of about 350 nm to about 500 nm. Some QTH bulbs may even emit a broader spectrum of light, although filters are typically used to limit the range of emitted light to the preferred range mentioned above.
One reason it is useful for the QTH bulb to emit a broad spectrum of light is because many dental compounds cure at different wavelengths. For example, camphorquinone is a common photo-initiator that is most responsive to light having a wavelength of about 460 nm to about 470 nm. Other light-curable products, however, including many adhesives are cured when they are irradiated by light wavelengths in the 350 nm to 400 nm range. Accordingly, QTH bulbs can be used to cure both camphorquinone initiated products as well as adhesives.
One problem with QTH bulbs, however, is that they generate a relatively high quantity of heat, making it impractical to place QTH bulbs on the portions of the light-curing devices that are inserted within the mouth of a patient. In particular, if the QTH bulbs were disposed at the tips of the light-curing devices, the heat generated by the QTH bulbs could burn or agitate the sensitive mouth tissues of the patient. Accordingly, the QTH bulbs are typically disposed remotely from the portion of the light-curing device that is inserted within a patient's mouth. The heat generated by QTH bulbs also represents wasted energy, which increases the power requirement to achieve a desired light intensity.
To channel and direct the light emitted by a QTH bulb to the desired location within a patient's mouth, existing curing lights must utilize light guides, such as fiber optic wands and tubular light guides, or special reflectors. Although fiber optic wands and reflectors are useful for their intended purposes, they are somewhat undesirable because they can add to the cost and weight of the equipment, thereby increasing the overall cost and difficulty of performing the light-curing dental procedures.
In an attempt to overcome the aforementioned problems, some light-generating devices have been manufactured using alternative light generating sources, such as light-emitting diodes (LEDs) which are generally configured to only radiate light at specific wavelengths, thereby eliminating the need for special filters and generally reducing the amount of input power required to generate a desired output of radiation.
LEDs are particularly suitable light sources because they generate much less heat than QTH bulbs, thereby enabling the LEDs to be placed at the tip of the curing lights and to be inserted directly within the patient's mouth. This is particularly useful for reducing or eliminating the need for light guides such as optical fiber wands.
One limitation of LEDs, however, is that they are only configured to emit a narrow spectrum of light. For example, a 460 nm LED or LED array will generally only emit light having a spectrum of 460 nm±30 nm. Accordingly, a light curing device utilizing a 460 nm LED light source will be well designed to cure camphorquinone initiated products, but will not be suitable for curing adhesives that are responsive to light in the 400 nm±30 nm range. Likewise, a light-curing device utilizing a 400 nm light source may be suitable to cure some adhesives, but will be unsuitable for curing camphorquinone initiated products.
In an attempt to overcome this limited utility, some light generating devices have been manufactured that include multiple LEDs configured to emit light at different wavelengths. However, because the different wavelengths of light are generated at different points (in contrast to a QTH bulb, or light redirected through a light guide, for example), it can be difficult to produce sufficient intensities of desired wavelengths across the full footprint of light emitted by the device. In other words, there are often “hot” and “cold” areas within the footprint of light generated with respect to any given wavelength.
In view of the foregoing, there exists a need to develop dental curing lights including multiple LEDs capable of providing more even intensities of any given wavelength across the full footprint of light emitted. It would be a further improvement to provide a dental curing light capable of better blending different wavelengths across the full footprint of light emitted in order to provide a broader spectrum of light across the full footprint.